Filter arrangement

ABSTRACT

A filter arrangement with a cellular structure in which a plurality of filter chambers extend in the direction of the medium to be filtered. There is a filter cloth or fabric attached to each of the two sides of a cell frame which closes the filter chambers on both sides. The filter chambers are each provided with a filling of predominantly active charcoal granules. To achieve a simple and advantageous structure of the filter arrangement, the cellular structure is in the form of a rectangular cell frame each with rectangular filter chambers, preferably made of synthetic resin. Appropriate, right-angled partition walls inside the cell frame and the installation of reinforcement members can result in filter chambers of optimum size.

The invention relates to a filter arrangement with a plurality of filterchambers, according to the preamble of the main claim.

STATE OF THE ART

A filter arrangement having a plurality of filter chambers with arectangular cellular frame is disclosed in GB 2,298,053 B, wherein thefilter chambers are each filled with active charcoal. The cellularstructure of these filter chambers is a honeycomb structure which ismade either of pressed paper, of cellulose or of metal. On both sides ofthis honeycomb structure, a permeable filter sieve which is permeable tothe medium to be filtered is adhered with the active charcoal included.For adhesion, the end faces of the honeycomb structure have a liquidadhesive applied thereto which hardens after the respective filter sieveis set in place.

A disadvantage of the known honeycomb structure is its relativelyexpensive manufacture, since as a rule it can be made only in one piece,and in the marginal area of the honeycomb structure it necessarilyresults in changes in the size of the filter chambers. Because in mostapplications a smooth cell frame is necessary, since the entire filterarrangement must be inserted into another apparatus, the filter chambersat the margins a substantially smaller passage surface area in order tostraighten out the chambers. In addition to the extra cost ofmanufacture, the throughput of the medium to be filtered is in this casedistributed non-uniformly.

OBJECT OF THE INVENTION

It is the object of the invention to provide a filter arrangement thatis easy to manufacture and forms an optimum passage surface for themedium to be filtered.

ADVANTAGES OF THE INVENTION

The filter arrangement of the kind referred to in the beginning isadvantageously further developed by the invention in that a cellularframe can be provided in a simple manner with intermediate walls, sothat rectangular or square filter chambers are formed. The filterchambers in the case of a given height of the cellular frame aredimensioned so that a volume of the active charcoal granules can beloaded into it that will be favorable to the filtering process.

Since the rectangular cell frame with its intermediate partition wallscan be formed of synthetic resin grids that may already be standardized,it is possible to press or fuse the filter fabric for the enclosure ofthe active charcoal in the filter chambers, in an at least partiallyfitted manner under the influence of heat onto the faces of the cellframe and partition walls. For this purpose, the filter fabric ispreferably made from a polyester sieve fabric. After the cell frame andthe partition walls are joined to the first filter fabric, the activecharcoal is filled into the filter chambers and enclosed by theattachment of the second filter fabric as described above.

An optimum filtering action can be achieved advantageously by a layeredarrangement of different granules, since in its direction of the flowthe medium to be filtered can pass through a succession of granularstructures adapted to the particular particles to be removed.

In another advantageous embodiment it is also possible to produce thecell structure in such a way that the filter fabric is initiallyintroduced into a corresponding mold and then the cell frame with thepartition walls is subsequently formed thereon by a plastic injectionmolding process.

A secure and strong enclosure of the active charcoal granules can beachieved in a simple manner after the introduction (filling) of thecharcoal granules by the shrinking, as defined in the dependent claims,of bulges created in at least an outer filter sieve by embossing or bythe filling.

It has proved to be especially advantageous to make the size of thepassage surface of the individual cells to be about 400 mm² or slightlyless. The active charcoal granules preferably have a grain size of about8×12, and can also be mixed additionally with polyurethane foam or otherresilient plastic particles. By the admixture of the plastic particles apermanent bias (prestress) can be produced in the granules whichprevents any separation of the active charcoal particles as well asnoise caused by their movement. Also, the resistance to flow and theadsorptive property of the filter arrangement can be positivelyinfluenced by an appropriate mixture and a possibly modified size of theactive charcoal granules.

By the additional use of a tension anchor as a reinforcing elementaccording to one of the dependent claims, it is advantageously possiblefor the filter chambers to be enlarged up to four times the sizereferred to above. This eliminates a number of partition walls in afilter arrangement of the same external size, thereby increasing thetotal filter volume. The tension anchor can be fastened in a simplemanner by a cross-shaped mount or support on the bottom of the filterchamber. Alternatively, the subsequent insertion of a rod or rivet as atension anchor is possible, which can be pushed through at least onefilter fabric and be held thereon.

Other advantageous embodiments are described in the further dependentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained with reference to a working embodimentillustrated in the drawing in which:

FIG. 1 is a view of a filter arrangement with filter chambers;

FIG. 2 is a detail view of a filter chamber with a tension anchor as areinforcing element;

FIG. 3 is a detail of a pre-embossed outer filter sieve, and

FIG. 4 is a section through a filter chamber with layers of granules.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a filter arrangement 1 which comprises a rectangular cellframe 2 with partition walls 3 and 4 of synthetic resin (polypropylene,for example). The partition walls 3 and 4 as well as in the outer partof the cell frame 2 form filter chambers 5 which are filled withgranules 6 of active charcoal, admixed in some cases with polyurethanefoam or other pieces of synthetic resin. The filter chambers 5 can befilled with a mixture of active charcoal granules 6 having differentcompositions and a substantially uniform particle size. In addition, theactive charcoal granules 6 may be impregnated with an impregnatingagent. The filter chambers 5 are closed off on both sides by a filterfabric 7, for example, a polyester sieve fabric.

In the illustrated embodiment, the filter fabric 7 can be installed inthis embodiment by pressing it under the influence of heat into the endfaces of the partition walls 3 and 4 as well as the cell frame 2. In analternative method of manufacture the cell structure 2, 3, 4 isinjection molded onto the first filter fabric 7. After the formation ofthe initially open filter chambers 5, the active charcoal granules andthe admixture if any are put into them, and then the cell frame 2 isclosed off with the second filter fabric 7 in the same manner asdescribed above.

On the outside of the cell frame 2 a gasket 8 is added, which upon theinsertion of the filter arrangement 1 into an apparatus, seals thefilter arrangement in such a way that no bypass of the medium willoccur.

In FIG. 2 there is shown a detail of a filter chamber 5 in the interiorof which a reinforcing element 9 is introduced which assures amechanical stabilization of the active charcoal granules and of theoptional admixture. The reinforcing element 9 can be constructed, forexample, in the form of a tension anchor which is held by a crosssupport on the bottom of the filter chamber 5. Other alternatives arepossible; for example, the reinforcing element 9 can be in the form of apin or rivet and extend possibly only between some of the walls orcorners of the filter chamber 5. In this case, for example, the filterfabrics 7 could be penetrated in order to fasten the reinforcing element9.

In the embodiment of a filter arrangement according to FIG. 3, the outerfilter fabric 7 can be domed or bulged and applied to the cell frame 2with the partition walls 3 and 4. After the introduction of the activecharcoal granules 7, the filter fabric 7 is shrunk by heating to therebyproduce a flat filter fabric surface again. The filter fabric 7 can alsobe applied to the cell frame 2 with the partition walls 3 or 4 in such away that it is bulged by the filling with the active charcoal granules 7and can thereafter be shrunk as described above.

In the embodiment according to FIG. 4, layers 6a and 6b of active carbongranules having different compositions and different grain sizes arearranged in the filter chambers 5. The layers 6a and 6b are separatedfrom one another by additional layers of sieve fabric, so that themedium to be filtered will flow through the layers one after the other.

We claim:
 1. A filter arrangement comprising a cell structure comprisingan outer frame and a plurality of intermediate partition walls disposedwithin the cell frame at right angles to define a plurality ofrectangular filter chambers extending in a flow direction of a mediumwhich is to be filtered; first and second filter fabric layers arrangedrespectively on opposite end faces of the cell structure so as to closeoff both ends of the filter chambers, a filling comprised at leastpredominantly of active charcoal granules disposed in said filterchambers between the first and second filter fabric layers, andreinforcing elements for mechanically stabilizing the active charcoalgranules disposed in the filter chambers, said reinforcing elementsbeing secured to a layer of said filter fabric by a pin or rivet whichpasses through the filter fabric layer.
 2. A filter arrangementaccording to claim 1, wherein the filling in the filter chamberscomprises a mixture of active charcoal granules having differentcompositions and a substantially uniform particle size.
 3. A filterarrangement according to claim 1, wherein the filling in the filterchambers comprises a plurality of layers of active charcoal granuleshaving different compositions and unequal grain sizes, adjacent layersof granules being separated from each other by an interposed furtherfilter fabric layer, whereby a medium to be filtered must flow throughthe layers of active charcoal granules one after the other.
 4. A filterarrangement according to claim 1, wherein the cell frame and thepartition walls are made of a synthetic resin that can be softened ormelted by the application of heat, and the respective first and secondfilter fabric layers are pressed into softened or melted surfaces of thecell frame and partitions to bond the fabric layers to the frame andpartitions.
 5. A filter arrangement according to claim 4, wherein thefirst filter fabric layer is pressed into softened or melted surfaces onone end of the frame and partitions and bonded thereto prior to fillingthe active charcoal granules into the filter chambers.
 6. A filterarrangement according to claim 1, wherein the cell frame and thepartition walls are injection molded onto the first filter fabric layer.7. A filter arrangement according to claim 1, wherein the filter fabriclayers are made from a polyester sieve fabric.
 8. A filter arrangementaccording to claim 1, wherein at least one of said first and secondfilter fabric layers is applied bulged onto the cell and frame andintermediate partitions, and after introduction of the active charcoalgranules into the filter chamber, the bulged layer is shrunk to producea flat filter surface, whereby the granules in the filter chamber arecompressed.
 9. A filter arrangement according to claim 1, wherein afterthe first filter fabric layer is affixed to the cell frame andintermediate partitions, said first fabric layer is bulged by fillingthe filter cells with active charcoal granules, after which the secondfabric layer is affixed to the opposite end face of the cell frame andintermediate partitions, and the bulged layer is then shrunk to producea flat filter surface, whereby the granules in the filter chamber arecompressed.
 10. A filter arrangement according to claim 1, wherein eachfilter chamber has a square cross section defining a passage area ofabout 400 mm² for a flow of a medium to be filtered.
 11. A filterarrangement according to claim 1, wherein said active charcoal granulesare mixed with pieces of resilient synthetic resin.
 12. A filterarrangement according to claim 11, wherein said pieces of resilientsynthetic resin are pieces of resilient polyurethane resin foam.
 13. Afilter arrangement according to claim 1, wherein the active charcoalgranules are impregnated with an impregnating agent.
 14. A filterarrangement according to claim 1, wherein said reinforcing elements aresupported between at least two opposite walls or corners and comprisinga tension anchor, said anchor being supported by a cross element on thebottom of the filter chamber.
 15. A filter arrangement according toclaim 14, wherein said reinforcing element comprises a tension anchor,said anchor being supported by a cross element on the bottom of thefilter chamber.
 16. A filter arrangement according to claim 1, furthercomprising a gasket adhesively attached to an outer margin of said cellframe on at least one side thereof.